The invention relates to a picture display device comprising a picture display tube a cathode of which is coupled to an emitter-follower drivable by a video preamplifier, a negative feedback signal input of this video preamplifier being coupled to an output of a negative feedback circuit and the collector of the emitter-follower being coupled to an input of a beam current measuring circuit.
Valvo Technische Information 830208 discloses a picture display device of the above-defined type, wherein an input of the negative feedback circuit is connected to an output of the circuit by which the emitter-follower is driven. The direct current flowing in the negative feedback circuit can then not affect the beam current measuring circuit.
It has been found that this circuit cannot satisfy the increasingly higher requirements imposed on the picture quality, as several types of distortions occur which in future might be experienced as annoying.